Field of the Invention
This invention relates to and is useful for selectively controlling the angle of a well hole or a borehole as it is cut through earth material or the like. More particularly, the present invention relates to a magnetostrictive or electrostrictive deflectable collar to be connected in a drill string. The deflectable collar can be energized to slightly bend or articulate the drill string or an attached drill bit to change the advancement angle of the borehole.